Muzzle brake and firearm

ABSTRACT

A muzzle brake as an exemplary muzzle brake has an inner tubular portion, an outer tubular portion, and a lid portion. A tip portion of a gun barrel is fixed to the inside of the inner tubular portion. A space is formed inside the inner tubular portion on an extension of a muzzle. A plurality of first gas-guiding holes is formed in the vicinity of the muzzle. A fired gas passes through the first gas-guiding holes from the muzzle, and is guided to the space between the inner tubular portion and the outer tubular portion.

TECHNICAL FIELD

The present invention relates to muzzle brake and a firearm. In particular, the invention relates to a muzzle brake and firearm which can reduce efficiently the influence of the gas at the time of firing.

BACKGROUND ART

A gunnery such as a gun and an artillery fires a bullet from a gun barrel using the pressure of the combustion gas of a gunpowder. At the time of firing a bullet, the powerful gas pressure inside a gun barrel generates the repercussion toward a shooter as well as the reaction posteriorly acting on the gun.

Moreover, due to the repercussion caused by the gas the of the gun raises upward, thereby leading to a phenomenon called a “muzzle jump” in which a muzzle of a gun turns up. Due to the repercussion caused by the gas the gun retreats to hit the shoulder of the shooter, thereby inflicting a physical pain or injury on the shooter. The accuracy of fire at the time of firing is also reduced. Furthermore, an influence may be exerted on the shooting posture of the following bullet.

For the above reasons, a muzzle brake for reducing the repercussion caused by the gas at the time of firing is attached at the tip of a gun or an artillery. The muzzle brake has a tubular or box-shaped contour, and vents the gas to an atmosphere through a hole formed in the side face thereof to decrease the repercussion. Such muzzle brake has been proposed by, for example, Patent Document 1

Patent Document 1 discloses a muzzle brake 100 as shown in FIG. 6. The muzzle brake 100 consists of a first main body 101 and a second main body 102. Both of them are cylindrically formed. Moreover, a plurality of through-holes is formed in the periphery of the first main body 101 and the second main body 102.

Moreover, the muzzle brake 100 is attachable to a gun barrel. Although muzzle brake 100 is a device for a gun barrel, a basic configuration where the through-hole is formed is common in the muzzle brake which is mountable to a gun.

Moreover, devices such as a flash hider which suppresses a firing flash and a silencer which suppresses a firing sound have a configuration similar to the muzzle brake. These are attached at the tip of a gun barrel like the muzzle brake, and is operable with the through-hole and an internal space.

CITATION LIST Patent Literature

[PLT 1]

Japanese Patent Publication H10-300392(A)

SUMMARY OF INVENTION Technical Problem

The muzzle brake as disclosed in Patent Document 1 diffuses the gas through the through-hole to the atmosphere to reduce the repercussion. However, a part of gas diffused from the muzzle of a gun creates the pressure which pushes a gun barrel back, and sufficient repercussion suppressive effect cannot be thus obtained.

Although a part of gas is diffused, all of the gas used for firing cannot be diffused immediately. Due to the action of the gas remaining in the gun barrel, the repercussion to a gun barrel easily occurs.

Moreover, the gas diffused from the through-hole may be reflected by the wall of a building, a ground, and etc. thereby blurring a gun barrel. Due to the blur of the gun barrel, the positon of the gun muzzle become unstable, and accuracy of fire will thus falls.

Moreover, the firing sound easily spreads around through the through-hole formed in the side surface and become loud. If the firing sound becomes loud, a shooter is not only exposed to the loud sound, and the location of the shooter is recognized.

As the gas is diffused through a plurality of the through-holes, disturbance of the fired gas may occur, thereby affecting the course of a bullet, and falling the accuracy of fire. Furthermore, the gas diffused through the through-hole facing the ground side raises a soil or a cloud of dust, and interrupts the view of the shooter.

Although the flash hider that is mounted to the gun barrel may have a function of the muzzle brake, the firing flash is discharged through the plurality of through-holes, which may be a danger of doing a damage to the surrounding human being.

Moreover, the silencer guides the gas from the gun barrel, accumulates the gas in a plurality of air chambers which is formed by the division of the interior of a main body, reduces a pressure, and then diffuse the gas. However, the consumption of an inner member such as a partition plate, caused by the pressure of gas is remarkable, and the partition plate should be exchanged frequently.

In order to overcome the above drawbacks and problems, the invention provides a muzzle brake and firearm which can reduce efficiently the influence of the gas at the time of firing.

Solution to Problem

In order to attain the above objective, in one aspect of the invention, a muzzle brake is provided with a substantially tubular inner wall portion having a first hole formed therein and in which a muzzle of a gun barrel that is inserted into the inner wall portion is located adjacent to the first hole and is capable of being fixed to the inner wall portion; an outer wall portion substantially surrounding the inner wall portion; a first blocking portion arranged closer to a location into which the gun barrel is inserted than a location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a second blocking portion arranged more opposite to the first blocking portion than the location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a substantially tubular piston which is movable in a state where an area between the first hole and the first blocking portion comes in contact with the inner wall portion and the outer wall portion; a piston-receiving member with an elasticity arranged between the piston and the first blocking portion and being movable in the area between the first hole and the first blocking portion.

In this regard, by virtue of the substantially tubular inner wall portion which the gun barrel can be inserted into and then fixed to, the muzzle brake can be mounted to the gun barrel.

Moreover, by virtue of the inner wall portion having the first hole formed therein and in which the muzzle of the gun barrel that is inserted into the inner wall portion is located adjacent to the first hole and is capable of being fixed to the inner wall portion, the gas generated at the time of firing can easily flow to the first hole. As such, the gas can be guided from the muzzle and the inner all portion to the first hole.

Moreover, the outer wall portion substantially surrounding the inner wall portion can surround the gun barrel and the inner wall portion so as to form the space between the inner wall portion and the outer wall portion. In other words, the gas generated at the time of firing can be guided to and temporarily held in this space.

Moreover, since the second blocking portion is arranged more opposite to the first blocking portion than the location where the first hole is formed to block the clearance between the inner wall portion and the outer wall portion, the repercussion caused by the pressure of the gas diffused outside and of pushing the gun barrel and the muzzle brake posteriorly can be reduced. In other word, the second blocking portion receives or take the pressure of the gas diffused outside and the pressure of the fired gas guided from the first hole to offset and reduce the repercussion caused by the gas diffused outside.

Moreover, since the second blocking portion is arranged more opposite to the first blocking portion than the location where the first hole is formed to block the clearance between the inner wall portion and the outer wall portion, it can block a location or side opposite to a side or location where the gun barrel is inserted into the space between the inner wall portion and the outer wall portion, thereby allowing the gas to be held in the space. In other words, the gas is held in the space without being diffused outside, thereby gradually reducing the pressure of the gas.

Moreover, by virtue of the substantially tubular piston which is movable in a state where an area between the first hole and the first blocking portion comes in contact with the inner wall portion and the outer wall portion, the gas diffusing from the first hole toward the first blocking portion can be taken or received. In other words, the pressure caused by the surplus gas which cannot be settled or received in the space adjacent to the second blocking portion can be taken or received, thereby allowing for the reduction of the repercussion.

Moreover, by virtue of the substantially tubular piston which is movable in a state where an area between the first hole and the first blocking portion comes in contact with the inner wall portion and the outer wall portion, the piston is pressed or pushed by the pressure of the gas to move. As a result, the volume of the space which can hold the gas therein is enlarged or increased. In other words, a greater amount of the gas can be held inside the muzzle brake, and the repercussion caused by the gas can be reduced.

Moreover, by virtue of a substantially tubular piston which is movable in a state where an area between the first hole and the first blocking portion comes in contact with the inner wall portion and the outer wall portion, the positon of the gun barrel can be stabilized. In other words, the piston which is pushed by the pressure of the gas moves in a direction substantially parallel to the gun barrel to reduce a blur of the gun barrel caused by the repercussion of the gas, as well as maintain the position of the gun barrel.

Moreover, by virtue of the piston-receiving member with elasticity arranged between the piston and the first blocking portion and being movable in the area between the first hole and the first blocking portion, grater pressure can be taken or received by the piston. In other words, the piston-receiving member can be contracted to receive the piston or push back the piston.

Moreover, by virtue of the piston-receiving member with an elasticity arranged between the piston and the first blocking portion and being movable in the area between the first hole and the first blocking portion, the piston and the piston-receiving member can move in a state where they are pushed by the pressure of the gas, thereby enlarging or increasing the volume of the space for holding the gas therein. In other words, a greater amount of the gas can be held in the muzzle brake, thereby reducing the repercussion caused by the gas.

Moreover, by virtue of the first blocking portion arranged closer to a location into which the gun barrel is inserted than a location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion, the piston-receiving member which moves due to the pressure of the gas can be stopped or blocked. In other words, the piston-receiving member which is pushed by the pressure of the gas can contract or extend.

Moreover, in a case where the piston is rotatable, and a center of gravity is biased in the piston, the center of gravity of the piston can be always maintained in a perpendicular and downward direction even when the direction or orientation of the gun barrel is changed or modified in a circumferential direction. In other words, when the gun is fired in an inclined manner, the above configuration can sufficiently mitigate the phenomenon that due to the repercussion of the gas the gun barrel raises upward.

Moreover, in a case where the muzzle brake is provided with a protruding portion which is located between the first hole and the piston, and protrudes from the inner wall portion toward the outer wall portion, the piston is prevented from moving toward the second blocking portion rather than the first hole. In other words, the gas is hit by the piston at the first blocking portion side rather than the first hole side, thereby allowing the piston to securely move toward the gun barrel.

Moreover, in a case where the first blocking portion has a first openable and closable opening portion, the space formed between the inner wall portion and the outer wall portion can be opened at the first blocking portion side. In other words, when the piston and the piston-receiving member are exhausted, they can be easily exchanged.

Moreover, in a case where the second hole is formed on a peripheral surface (i.e., an outer periphery) of the outer wall portion and in an at least part of an area where the piston is movable, a part of the gas pushing the piston toward the first blocking member can be guided from the space between the inner wall portion and the outer wall portion to the second hole. In other words, the surplus gas can be further diffused to the second hole.

Moreover, in a case where the muzzle brake is provided with a guiding outer wall portion substantially surrounding the outer wall portion, it can surround the gun barrel, the inner wall portion and the outer wall portion so as to form the space between the guiding outer wall portion and the outer wall portion. In other words, the gas created at the time of firing can be further guided to and temporarily held in this space.

Moreover, in a case where the muzzle brake is provided with a third blocking portion located more closer to the location into which the gun barrel is inserted than a location where the second hole is formed, and configured to block a clearance between the outer wall portion and the guiding outer wall portion, the location or side into which the gun barrel is inserted in the space between the outer wall portion and the guiding outer wall portion can be blocked, and the gas can be thus held in the space. In other word, the gas can be held in the space without being diffused outside, thereby gradually reducing the pressure.

Moreover, in a case where the muzzle brake is provided with a fourth blocking portion located more opposite to the third blocking portion than a location where the second hole is formed, and configured to block a clearance between the outer wall portion and the guiding outer wall portion, and the third hole formed in the fourth blocking portion, the gas can be guided into the space formed between the outer wall portion and the guiding outer wall portion, and simultaneously discharged outside through the third hole. In other words, the gas can be ultimately diffused outside while reducing the pressure of the gas.

Moreover, in a case where the muzzle brake is provided with a partition portion having a fourth hole formed in at least a part thereof, and configured to block a clearance between the outer wall portion and the guiding outer wall portion, the gas can be guided through the fourth hole into the space arranged in the partition portion. In other words, by increasing a period of time needed to move the gas, the gas can be easily cooled, and the pressure of the gas can be further reduced.

Moreover, in a case where the muzzle brake is provided with a plurality of the partition portions, a period of time needed to move the gas is increased, thereby sufficiently cooling the gas.

Moreover, in a case where the muzzle brake is provided with a plurality of the partition portions, and the neighboring partition portions are different from each other in an arrangement of the fourth hole in a plane which is substantially perpendicular to a lengthwise direction of the guiding outer wall portion, the cooling effect of the gas can be further enhanced. In other words, the location or arrangement of the fourth hole through which the gas passes is different between the partition portions, and the gas should move to the location of the fourth hole in each partition portions, thereby increasing a period of time needed for the movement.

Moreover, in a case where the muzzle brake is provided with a second openable and closable opening formed in the third blocking portion, the space formed between the outer wall portion and the guiding outer wall portion can be opened at the third blocking portion side. In other words, when the partition portion arranged in the space is exhausted, it can be easily exchanged.

In order to attain the above objective, in another aspect of the invention, a muzzle brake is provided with a substantially tubular inner wall portion having a first hole and a second hole spaced apart from the first hole, and in which a muzzle of a gun barrel that is inserted into the inner wall portion is located adjacent to the second hole and is capable of being fixed to the inner wall portion; an outer wall portion substantially surrounding the inner wall portion; a first blocking portion arranged more opposite to the location into which the gun barrel is inserted than a location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a second blocking portion arranged closer to the location into which the gun barrel is inserted than a location where the second hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; and a protruding portion located at the first hole adjacent the second hole on a peripheral surface of the inner wall portion and protruding from the inner wall portion toward the outer wall portion.

By virtue of the substantially tubular inner wall portion in which the muzzle of the gun barrel that is inserted into the inner wall portion is located adjacent to the second hole and is capable of being fixed to the inner wall portion, the muzzle brake can be mounted to the gun barrel.

By virtue of the second hole, and the inner wall portion in which a muzzle of a gun barrel that is inserted into the inner wall portion is located adjacent to the second hole and is capable of being fixed the inner wall portion, the gas generated at the time of firing can easily flow to the second hole. As such, the gas can be guided from the muzzle and inner wall portion to the second hole.

By virtue of the outer wall portion substantially surrounding the inner wall portion, the outer wall portion can surround the gun barrel and the inner wall portion to form a space between the inner wall portion and the outer wall portion. In other words, the gas generated at the time of firing can be guided to and temporarily held in this space.

Moreover, by virtue of the inner wall portion having the first hole and the second hole spaced apart from the first hole, and the outer wall portion substantially surrounding the inner wall portion, the gas having been guided from the second hole into the space between the inner wall portion and the outer wall portion can be guided again from the first hole into the space inside the inner wall portion. In other words, the flow of the gas having passed the first hole can collide against the gas to be diffused outside from the muzzle without passing through the first hole, thereby weakening the power or force of the gas diffused without passing through or entering the first hole.

Moreover, by virtue of the protruding portion located at the first hole adjacent the second hole on a peripheral surface of the inner wall portion and protruding from the inner wall portion toward the outer wall portion, the volume of the space between the inner wall portion and the outer wall portion in the vicinity of the first hole can be decreased. In other words, as the flow rate of the gas in the vicinity of the first hole becomes greater than that of the gas in the vicinity of the second hole, it can vigorously collide against the gas diffused without entering or passing through the first hole.

In order to attain the above objective, in still another aspect of the invention, a firearm is provided with a gun barrel having a gun barrel hole formed in an area thereof adjacent to a muzzle, and a muzzle brake, which comprises: a substantially tubular inner wall portion having a first hole formed in an area thereof corresponding to the gun barrel hole, and to which the gun barrel can be fixed inside the inner wall portion; an outer wall portion substantially surrounding the inner wall portion and having a second hole formed closer to a location into which the gun barrel is inserted than the location where the first hole is formed; a first blocking portion arranged closer to the location into which the gun barrel is inserted than the location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a second blocking portion arranged more opposite to the first blocking portion than the location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a guiding outer wall portion substantially surrounding the outer wall portion; a third blocking portion located more closer to the location into which the gun barrel is inserted than a location where the second hole is formed, and configured to block a clearance between the outer wall portion and the guiding outer wall portion; a fourth blocking portion located more opposite to the third blocking portion than a location where the second hole is formed, and configured to block a clearance between the outer wall portion and the guiding outer wall portion; a third hole formed in the fourth blocking portion; and a partition portion having a fourth hole formed in at least a part thereof, and configured to block a clearance between the outer wall portion and the guiding outer wall portion.

Moreover, by virtue of the gun barrel having the gun barrel hole formed in an area thereof adjacent to the muzzle, the gas generated at the time of firing can be diffused outside from the gun barrel hole.

Moreover, by virtue of the inner wall portion to which the gun barrel can be fixed thereinto, the muzzle brake can be mounted to the gun barrel.

Moreover, by virtue of the inner wall portion having the first hole formed in an area thereof corresponding to the gun barrel hole, the gas diffused through the gun barrel hole can be guided through the first hole.

Moreover, by virtue of the outer wall portion substantially surrounding the inner wall portion and having the second hole formed closer to a location into which the gun barrel is inserted than the location where the first hole is formed, the space between the inner wall portion and the outer wall portion can be formed, and the gas having passed through the first hole can be guided to the second hole. In other words, while the gas is guided into the space, it is cooled to gradually reduce the pressure thereof.

Moreover, the guiding outer wall portion substantially surrounding the outer wall portion can surround the gun barrel, the inner wall portion, and the outer wall portion so as to form the space between the outer wall portion and the guiding outer wall portion. In other words, the gas created at the time of firing is guided to and temporality held in the space.

Moreover, by virtue of the fourth blocking portion located more opposite to the third blocking portion than a location where the second hole is formed, and configured to block a clearance between the outer wall portion and the guiding outer wall portion, and the third hole formed in the fourth blocking portion, the gas can be discharged outside from the third hole while being guided into the space formed between the outer wall portion and the guiding outer wall portion. In other words; the gas can be ultimately diffused outside while reducing the pressure of the gas.

Moreover, by virtue of the partition portion having the fourth hole formed in at least a part thereof, and configured to block the clearance between the outer wall portion and the guiding outer wall portion, the gas can be guided through the fourth hole to the space in which the partition portion is arranged.

Advantageous Effects of Invention

A muzzle brake in accordance with some embodiments of the invention can reduce efficiently the influence of the gas at the time of firing. Moreover, the firearm in accordance with some embodiments of the invention can reduce efficiently the influence caused by the gas at the time of firing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view showing an exemplary first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing an example of a second embodiment of the present invention.

FIG. 3(a) is a schematic view showing a configuration of a partition plate (1) and FIG. 3(b) is a schematic view showing a configuration of a partition plate (2).

FIG. 4 is a schematic sectional view showing an example of a third embodiment of the present invention.

FIG. 5 is a schematic sectional view showing an example of a fourth embodiment of the present invention.

FIG. 6 is a schematic view showing a conventional muzzle brake.

DESCRIPTION OF EMBODIMENTS

Hereinafter, referring to the drawings an embodiment of a muzzle brake in accordance with the present invention is described in order to develop an understanding of the present invention.

FIG. 1 is a schematic perspective view showing an example of the first embodiment of the present invention.

Referring to FIG. 1, a muzzle brake 1 which is an exemplary muzzle brake to which the present invention is applied is provided with an inner tubular portion 2, an outer tubular portion 3, and a lid portion 4.

Moreover, the tip portion of the gun barrel 5 is fixed to the inside of the inner tubular portion 2. A space is formed inside the inner tubular portion 2 on an extension of a muzzle 6. Moreover, a plurality of first gas-guiding holes 7 is formed adjacent to the muzzle 6. The gas at the time of firing passes through the first gas-guiding hole 7 from the muzzle 6, and is guided to the space between the inner tubular portion 3 and the outer tubular portion 4.

The outer tubular portion 3 surrounds the inner tubular portion 2. A space is formed between the outer tubular portion 3 and the inner tubular portion 2. Moreover, an opening is formed in the inner tubular portion 2 and the outer tubular portion 3 adjacent to the gun barrel 5, and a blocking portion 4 is formed near the location where a bullet is fired. Moreover, the opening adjacent the gun barrel 5 is closed by the lid portion 4 to form an openable and closable configuration. Moreover, the lid portion 4 has a configuration (not shown) which can be fixed to the gun barrel 5 by a screw.

Moreover, a substantially cylindrical piston 8 is arranged more closer to the gun barrel 5 than the first gas-guiding holes 7 such that it can be moved in a longitudinal direction of the inner tubular portion 2. The piston 8 comes in contact with the inner tubular portion 2 and the outer tubular portion 3, and takes a pressure of the gas to move (i.e. moves due to the pressure).

Moreover, the piston 8 is rotatably about the inner tubular portion 2 which comes in contact with an inner periphery of the piston 8. Moreover, a weight is partly in an area of the piston 8 such that the center of gravity is biased.

A spring 9 is arranged adjacent to the piston 8. The spring 9 supports the piston 8 such that the piston 8 which is pushed by the pressure of the gas moves toward the gun barrel 5. Moreover, the piston 8 and the spring 9 are not fixed, and each of them is movable between the first gas-guiding hole 7 and the lid portions 4. Moreover, a spring receptacle with a bearing (not shown) is arranged in both ends of the spring 9.

A substantially cylindrical stopper 10 is formed at the first gas-guiding hole 7 side adjacent to the gun barrel 5 in the inner tubular portion 2. The stopper 10 prevents the piston 8 from moving toward the first gas-guiding hole 7.

The number and the shape of the first gas-guiding hole 7 are determined such that the gas at the time of firing can be guided to the space between the inner tubular portion 2 and the outer tubular portion 3, and are not particularly limited. A configuration where the plurality of holes is formed on the circumference of the inner tubular portion 2, a configuration where a slit-like opening is formed, and etc. may be employed.

Moreover, the lid portion 4 is not necessarily fixable to the gun barrel 5 by means of a screw. However, in view of the point that the muzzle brake 1 can be firmly fixed to the gun barrel 5, it is desirable that the lid portion 4 is fixable to the gun barrel 5 by means of the screw.

If the piston 8 can receive or take the pressure of the gas, the size and weight thereof are not limited. The size and weight of the piston 8 can be properly determined depending on the kinds of gun and bullet to which the piston 8 is mounted.

Moreover, the piston 8 is not necessarily formed such that it is rotatable and the center of gravity is biased. However, since raising the gun barrel 5 can be mitigated even in a case where the gun barrel 5 is shot in an inclined position, the piston 8 is preferably formed such that it is rotatable and the center of the gravity is biased.

The weight is not necessarily mounted in a part of piston 8. The configuration where the center of gravity is biased may be a configuration where a part of piston is made hollow.

Moreover, the spring 9 would be enough that it can support the piston 8 that is pushed by the pressure of the gas, and the shape and elasticity thereof are not particularly limited. The shape and elasticity can be properly determined depending on the kinds of gun and bullet used.

In addition, the movement distance between the piston 8 and the spring 9 can be adjusted by changing the weight of the piston 8 and the elasticity of the spring 9. If the volume of the space formed by the inner tubular portion 2 and the outer tubular portion 3 can be modified by changing the movement distance. For example, by lengthening the movement distance of the piston 8 and the spring 9 even when there is much quantity of the gas at the time of firing, the volume of the space can be sufficiently secured and the repercussion of the gas can be sufficiently reduced. As a result, the muzzle brake 1 is be adaptable to a variety of guns and bullets.

The piston 8 and the spring 9 are not necessarily non-fixating configuration. It would be enough that the piston 9 and the spring 9 can receive or take the pressure of the gas. For example, there may be considered a configuration where an end of the spring 9 is connected to the piston 8, and an opposite end of spring 9 away from the piston 8 is fixed to the inner tubular portion 2.

Moreover, the stopper 10 is not necessarily formed in the inner tubular portion 2. However, in view of the point that the movement of the piston 8 toward the first gas-guiding hole 7 is suppressed and the pressure of the gas coming from the first gas-guiding hole 7 is easily received or taken, it is desirable that the stopper 10 is formed in the inner tubular portion 2.

Moreover, the spring receptacle with the bearing is not necessarily arranged at the both ends of the spring 9. However, in view of the point that the movement of the piston 8 is sufficiently supported and the durability of the device is improved, it is desirable that the spring receptacle with the bearing is arranged at the both ends of the spring 9.

Moreover, it would be enough that the stopper 10 can suppress the migration of the piston 8 toward the first gas-guiding hole 7. The shape of the stopper 10 is not particularly limited. For example, the stopper 10 may be partly formed on the circumference of the inner tubular portion 2.

The application of the first embodiment of the present invention is described in order to develop an understanding of the present invention.

The motion of the gas and the reduction of the repercussion at the time of firing are as follows.

Firstly, at the time of firing, a bullet is fired from the muzzle 6 and a part of fired gas is diffused outside from the opening of the inner tubular portion 2 on the extension of the muzzle 6. The pressure created by the gas diffused outside serves as the repercussion which pushes the muzzle brake 1 and the gun barrel 5 posterior to a shooter.

Moreover, the gas having not been diffused outside passes through the first gas-guiding hole 7, and flows into the space between the inner tubular portion 2 and the outer tubular portion 3. This gas is held in the space for a definite period of time. After that, the gas is cooled and the volume of the gas contracts with the elapse of time. As a result, the pressure falls gradually. Due to the fall in the pressure, repercussion of gas becomes weaker.

Moreover, a part of the gas having passed through the first gas-guiding hole 7 is taken by the blocking portion 11, and exerts a pressure in a firing direction. The pressure serves as a force which pushes out the muzzle brake 1 and the gun barrel 5 in the firing direction.

That is, the pressure of the gas having passed through the first gas-guiding hole 7 can act counter to the pressure of the gas diffused outside on the border of the blocking portion 11, thereby reducing the repercussion caused by the gas diffused outside.

Moreover, among the gas having passed the first gas-guiding hole 7 the surplus gas which cannot be settled or received in the space at the blocking portion 11 side flows toward the piston 8. The piston 8 is pushed by the pressure of the surplus gas to move back. Moreover, the piston 8 is supported by the spring 9.

The piston 8 moves in a direction substantially parallel to the gun barrel 5 to reduce a blur of the gun barrel caused by the repercussion of the gas, and maintain the position of the gun barrel. Moreover, due to the contraction of the spring 9, the volume of the space can become larger, and the surplus gas can be also held in the space.

Moreover, the gas diffused outside and the gas remaining inside the gun barrel produce the repercussion in a lengthwise direction (i.e., the lengthwise repercussion) such that the muzzle brake 1 and the gun barrel 5 raises upward. However, since the piston 8 is rotatable and the center of gravity is biased, the center of gravity of the piston 8 is always located perpendicularly and downwardly, thereby suppressing effectively the lengthwise repercussion caused by the gas.

As such, the pressure of the gas guided to the inside of the muzzle brake 1 is used for pushing out the gun barrel 5 anteriorly as well as the movement of the piston 8. Moreover, the gas is held in the space for a definite period of time and is then cooled and the pressure falls gradually. Eventually the gas is diffused outside slowly from the opening of the inner tubular portion 2 on the extension of the muzzle 6.

As described previously, in the first embodiment of the present invention, the pressure of the gas guided to the inside of the muzzle brake 1 is used to offset the repercussion caused by the pressure of the gas diffused outside, thereby reducing the repercussion exerted on the gun barrel 5.

Moreover, the gas is held inside the muzzle brake 1 for a definite period of time, and the pressure of the gas is reduced with the elapse of time.

Moreover, due to the movement of the piston 8, the repercussion caused by the pressure of the gas and working posteriorly can be reduced. Furthermore, due to the configuration where the piston is rotatable and the center of gravity is biased, the lengthwise repercussion can be reduced. Furthermore, as the piston 8 moves, the position of the gun barrel 5 can be stabilized.

Moreover, since the fired gas is not spread or diffused from any site or area other than the opening of the inner tubular portion 2, the reflection of the gas hardly occurs in the topography of the surroundings such as a wall and a ground, and the blur of the gun barrel 5 becomes less. Moreover, the firing sound can be significantly reduced.

Moreover, since like the fired gas, the firing flame is not spread or diffused from any site or area other than the opening of the inner tubular portion 2, it shall be hard to do a damage caused by the firing flame to the surrounding human being.

Moreover, since the lid portion 4 is the openable and closable configuration, the piston 8 and the spring 9 can be easily exchanged, thereby improving the maintenance performance.

Moreover, since the piston is a tough configuration of being able to bear the repetitive movements, the consumption thereof caused by fired gas is not significant, thereby enhancing the durability of the device.

Next, a second embodiment of the invention is described. FIG. 2 is a schematic sectional view showing an example of the second embodiment of the present invention. FIG. 3(a) is a schematic view showing a configuration of a partition plate (1) and FIG. 3(b) is a schematic view showing a configuration of a partition plate (2).

Referring to FIG. 2, a large-caliber muzzle brake 12, an exemplary muzzle brake in accordance with the present invention has an inner tubular portion 13, an outer tubular portion 14, a guiding outer tubular portion 15, and a lid portion 16.

Moreover, a large-caliber gun barrel 17 is fixed to the inside of the inner tubular portion 13. In addition, since the second embodiment has the fundamental configurations of the inner tubular portion 13 and the outer tubular portion 14, the first gas-guiding hole 7 and the piston 8, the spring 9, the stopper 10, and the blocking portion 11 in common with the first embodiment, the detailed description in this regard is omitted.

As shown in FIG. 2, a second gas-guiding hole 18 is formed on a part of the outer periphery of the outer tubular portion 14. The second gas-guiding hole 18 is formed in the middle of the movement region of the piston 8 and in the vicinity of the location where the piston 8 is sufficiently pushed or pressed. The second gas-guiding hole 18 passes through a space between the inner tubular portion 13 and the outer tubular portion 14, and is configured to pass the gas having pushed the piston 8 therethrough.

Furthermore, the guiding outer tubular portion 15 surrounds the outer tubular portion 14 to provide a space between the guiding outer tubular portion 15 and the outer tubular portion 14. Furthermore, an opening is formed in both of the outer tubular portion 14 and the guiding outer tubular portion 15 adjacent to the gun barrel 5, and a blocking portion 19 is formed adjacent the location where the bullet is fired. Moreover, a third gas-guiding hole 20 is formed in the blocking portion 19 to diffuse the gas outside.

Moreover, the opening at the gun barrel 17 side is closed by the lid portion 16 to form an openable and closable configuration. Moreover, the lid portion 16 has a configuration which can be fixed to the gun barrel 17 by a screw.

Moreover, a plurality of partition plates 22 is arranged in the large-caliber muzzle brake 12 to partition the space formed between the outer tubular portion 14 and the guiding outer tubular portion 15. A fourth gas-guiding hole 23 is formed in the partition plate 22 to pass the gas therethrough.

Moreover, referring to FIG. 3, the location of the fourth gas-guiding hole 23 in the partition plate 22 is formed in two patterns. Both of FIG. 3(a) and FIG. 3(b) are viewed from the plane which substantially intersects with the lengthwise direction of the guiding outer tubular portion 15.

Referring to FIG. 3(a), a plurality of the fourth gas-guiding holes 23 is formed in the vicinity of the outer periphery of the partition plate 22. On the other hand, referring to FIG. 3(b), a plurality of the fourth gas-guiding holes 23 is formed in the vicinity of the inner periphery of the partition plate 22.

Referring to FIG. 2, these two partition plates 22 are alternately arranged in the large-caliber muzzle brake 12.

The number and the shape of the second gas-guiding hole 18 are determined such that the gas can be guided to an area at the gun barrel 17 side and the space between the outer tubular portion 14 and the guiding outer tubular portion 15, and are not particularly limited. A configuration where the plurality of holes is formed on the outer periphery of the outer tubular portion 14, a configuration where a slit-like opening is formed, and etc. may be employed.

Moreover, the second gas-guiding hole 18 is not necessarily formed in the vicinity of the location where the piston 8 is sufficiently pushed or pressed. However, in view of the point that the volume of the space between the inner tubular portion 13 and the outer tubular portion 14 is sufficiently utilized, it is desirable that the second gas-guiding hole 18 is formed in the vicinity of the location where the piston 8 is sufficiently pushed or pressed.

Moreover, the lid portion 16 is not necessarily formed as a configuration 21 which can be fixed to the gun barrel 17 by a screw. However, in view of the point that the muzzle brake 12 can be firmly fixed to the gun barrel 17, it is desirable that the lid portion 16 is formed as the configuration 21 which can be fixed to the gun barrel 17 by a screw.

Moreover, the large-caliber muzzle brake 12 is not necessarily provided with the partition plate 22. However, in view of the point of increasing a period of time needed to move the guided gas to enhance cooling effect and reduce sufficiently the pressure, it is desirable that the partition plate 22 is arranged in the muzzle brake 12.

Moreover, the two different partition plates where the arrangements of the fourth gas-guiding holes 23 are different from each other are not necessarily arranged in an alternate manner. However, in view of the point of increasing a period of time needed to move the guided gas to enhance cooling effect and reduce sufficiently the pressure, it is desirable that the two partition plates where the arrangements of the fourth gas-guiding holes 23 are alternately arranged.

Moreover, the arrangement of the partition plate 22 is not particularly limited. For example, a configuration where the partition plates are arranged one by one, and a configuration where a plurality of partition plates is coupled by a rod-like member and is thus integrated may be adopted. In the integrated configuration, the partition plate 22 can be exchanged as a whole, thereby improving the maintenance performance.

Moreover, a gun which can be provided with the large-caliber muzzle brake 12 is not particularly limited. For example, the large-caliber muzzle brake 12 may be mounted to a gun of 222-caliber and used.

The application of the second embodiment of the present invention is described in order to develop an understanding of the present invention.

The motion of the gas and the reduction of repercussion at the time of firing are as follows.

The greater the caliber of the large-caliber gun barrel 17 is, the greater the amount of the gas needed for the firing of the bullet is. Accordingly, the repercussion caused by the gas and exerted on the gun barrel become greater. In the second embodiment, the description is hereinafter made from the point that due to the gas the piston 8 is pushed and moved.

Firstly, the gas having passed through the first gas-guiding hole 7 and pushed the piston 8 among the gas occurring at the time of firing passes through the second gas-guiding hole 18 and flows into the space formed in the guiding outer tubular portion 15. This gas is held in the space for a definite period of time. After that, the gas is cooled and the volume of the gas contracts with the elapse of time. As a result, the pressure falls gradually. Due to the fall in the pressure, the repercussion of the gas becomes weaker.

Moreover, among the gas having passed the second gas-guiding hole 18 the surplus gas which cannot be settled or received in the space formed in the guiding outer tubular portion 15 flows toward the partition plate 22. The gas passes through the fourth gas-guiding hole 23 of the partition plate 22, and is guided into the space formed by the plurality of partition plates 22.

Moreover, the guided gas moves toward the fourth gas-guiding hole 23 of the partition plates 22. In this regard, the neighboring partition plates are different from each other in the location where the fourth gas-guiding hole 23 is formed. During this step, a period of time needed for the movement of the gas increases, thereby improving the cooling effect caused by the gas.

The gas having passed the fourth gas-guiding hole 23 of the partition plate 22 diffuses outside from the third gas-guiding hole 20 that is formed in the blocking portion 19. Furthermore, the gas held inside the large-caliber muzzle brake 12 is cooled and the pressure falls gradually. The gas is diffused outside slowly from the opening of the inner tubular portion 13 on the extension of a muzzle 24,

As described previously, in accordance with the second embodiment of the present invention, the pressure of the gas guided to the inside of the large-caliber muzzle brake 12 is used to offset the repercussion caused by the pressure of the gas diffused outside, thereby reducing the repercussion exerted on the gun barrel 17.

Moreover, due to the movement of the piston 8, the repercussion caused by the pressure of the gas and working posteriorly can be reduced. Furthermore, due to the configuration where the piston is rotatable and the center of gravity is biased the lengthwise repercussion can be reduced. Furthermore, as the piston 8 moves, the position of the gun barrel 17 can be stabilized.

By adopting the guiding outer tubular portion 15, the amount of the gas held inside can be increased, thereby being adaptable to a large-caliber gun.

Next, a third embodiment of the invention is described.

FIG. 4 is a schematic sectional view showing an example of a third embodiment of the present invention.

Referring to FIG. 4, a simplified muzzle brake 25, an exemplary muzzle brake in accordance with the present invention has an inner tubular portion 26 and an outer tubular portion 27.

Moreover, a gun barrel 28 is fixed to the inside of the inner tubular portion 26. Furthermore, a first gas-guiding hole 29 is formed adjacent to the location of the inner tubular portion 26 where the bullet is fired. Furthermore, a second gas-guiding hole 31 is formed in the vicinity of a muzzle 30 of the inner tubular portion 26.

Moreover, the gross-sectional area of the first gas-guiding hole 29 on the circumference (i.e., periphery) of the inner tubular portion 26 is less than the gross-sectional area of the second gas-guiding hole 31 on the circumference of the inner tubular portion 26.

Moreover, a protruding portion 32 is formed at the first gas-guiding hole 29 adjacent the gun barrel 28 side in the inner tubular portion 26. Due to the protruding portion 32 the volume of the space between the inner tubular portion 26 and the outer tubular portion 27 is reduced. For the above configuration, the flow rate of the guided gas can be increased, and the pressure of the gas flowing from the first gas-guiding hole 29 to the inner tubular portion 26 can be increased.

Furthermore, the outer tubular portion 27 surrounds the inner tubular portion 26 to provide a space between the outer tubular portion 27 and the inner tubular portion 26. Furthermore, a blocking portion 34 with an inclined surface 33 is formed in the vicinity of the second gas-guiding hole 31 in the inner tubular portion 26 and the outer tubular portion 27 at the gun barrel 5 side. Furthermore, a blocking portion 36 with a curved surface 35 is formed in the inner tubular portion 26 and the outer tubular portion 26 and adjacent to the location where a bullet is fired.

Moreover, an area which is located between the inner tubular portion 26 and the outer tubular portion 27 and adjacent to the gun barrel 28 from the blocking portion 34 is solid.

The number and the shape of the first gas-guiding hole 29 are determined such that the gas can be guided from the space between the inner tubular portion 26 and the outer tubular portion 27 to the space inside the inner tubular portion 26, and are not particularly limited. A configuration where the plurality of holes is formed on the peripheral surface of the inner tubular portion 26 and a configuration where a slit-like opening is formed, and etc. may be employed.

The number and the shape of the second gas-guiding hole 31 are determined such that the gas can be guided to the space between the inner tubular portion 26 and the outer tubular portion 27, and are not particularly limited. A configuration where the plurality of holes is formed on the peripheral surface of the inner tubular portion 26 and a configuration where a slit-like opening is formed, and etc. may be employed.

Moreover, the gross-sectional area of the first gas-guiding hole 29 on the circumference of the inner tubular portion 26 is not necessarily less than the gross-sectional area of the second gas-guiding hole 31 on the circumference of the inner tubular portion 26. However, in view of the point that the flow rate (i.e., the speed) of the gas passing through the first gas-guiding hole can be increased, and the repercussion caused by the gas diffused outside from the muzzle 30 can be further effectively reduced, it is desirable that the gross-sectional area of the first gas-guiding hole 29 on the circumference of the inner tubular portion 26 is less than the gross-sectional area of the second gas-guiding hole 31 on the circumference of the inner tubular portion 26.

Moreover, the blocking portion 34 does not necessarily have the inclined surface 33. However, in view of the point that the gas passing through the second gas-guiding hole 31 can be smoothly flowed in the firing direction and the force or power of the gas diffusing from the muzzle 30 to outside can be easily reduced, it is desirable that the blocking portion 34 has the inclined surface 33.

Moreover, the blocking portion 36 does not necessarily have the curved surface 35. However, in view of the point that the flowing gas can be smoothly flowed to the first gas-guiding hole 29, and the force or power of the gas diffusing from the muzzle 30 to outside can be easily reduced, it is desirable that the blocking portion 34 has the inclined surface 35.

The application of the second embodiment of the present invention is hereinafter described in order to develop an understanding of the present invention.

The motion of the gas and the reduction of repercussion at the time of firing are as follows.

Firstly, at the time of firing, a bullet is fired from the muzzle 30 and a part of the fired gas is diffused outside from the opening of the inner tubular portion 26 on the extension of the muzzle 30. The pressure created by the gas diffused outside serves as the repercussion which pushes the muzzle brake 25 and the gun barrel 28 posterior to a shooter.

Moreover, a part of the gas having not been diffused outside passes through the first gas-guiding hole 31, and flows into the space between the inner tubular portion 26 and the outer tubular portion 27. The gas flows along the inclined surface 33 of the blocking portion 34 to move in the firing direction (i.e., toward the location where the bullet is fired).

The flow rate of the gas having passed the gas through the second gas-guiding hole 31 is increased in the location of the protruding portion 32 to reach the blocking portion 36. The gas is taken by the blocking portion 36 to work the pressure in the firing direction. The pressure serves as a force to push out the simplified muzzle brake 25 and the gun barrel 28 in the firing direction.

That is, the pressure of the gas having passed through the second gas-guiding hole 31 can act counter to the pressure of the gas diffused outside on the border of the blocking portion 36, thereby reducing the repercussion caused by the gas diffused outside.

Moreover, the gas which reaches the location of the blocking portion 36 flows along the curved surface 35 to pass through the first gas-guiding hole 29. The gas having passed the first gas-guiding hole 29 collides against the gas to be diffused outside from the muzzle 30 without passing through the first gas-guiding hole 29, thereby weakening the power or force to reduce the repercussion.

The gas to be diffused outside with the weakened power is diffused outside from the opening of the inner tubular portion 26 on the extension of the muzzle 30.

As described previously, in accordance with the third embodiment of the invention the flow of the gas collides against the gas to be diffused outside to reduce the repercussion caused by the gas and exerted on the gas barrel.

Moreover, since the simplified muzzle brake 25 has a simplified configuration, it is hard to break and is easily attachable and removable.

Next, a fourth embodiment of the invention is described. FIG. 5 is a schematic sectional view showing an example of a fourth embodiment of the present invention.

Referring to FIG. 5, a gun 37, an exemplary firearm to which the invention is applied has a gun barrel 38 and a muzzle brake 39. A plurality of gun barrel holes 41 is formed in the vicinity of a muzzle 40 in the gun barrel 38.

The muzzle brake 39 has an inner tubular portion 42, an outer tubular portion, and a guiding outer tubular portion 44.

The gun barrel 38 is inserted into the inner tubular portion 42, and fixed to the gun barrel 38 by a screw fixing member 45. Furthermore, a plurality of first gas-guiding holes 53 is formed in a location corresponding to the gun barrel hole 41 of the inner tubular portion 42.

Furthermore, the outer tubular portion 43 surrounds the inner tubular portion 42 to provide a space between the outer tubular portion 43 and the inner tubular portion 42. Furthermore, a blocking portion 46 is formed in the inner tubular portion 42 and the outer tubular portion 43 adjacent the location where the bullet is fired. Moreover, a second gas-guiding hole 47 is formed on the outer periphery of the outer tubular portion 43 and adjacent to the gun barrel 38.

Moreover, the guiding outer tubular portion 44 surrounds the outer tubular portion 43 to provide a space between the guiding outer tubular portion 44 and the outer tubular portion 43. Furthermore, a blocking portion 48 is formed in the outer tubular portion 43 and the guiding outer tubular portion 44 adjacent to the location where the bullet is fired. Moreover, a third gas-guiding hole 49 is formed in the blocking portion 48 to diffuse the gas outside. Furthermore, a blocking portion 50 is formed in the outer tubular portion 43 and the guiding outer tubular portion 44 at the gun barrel side.

A plurality of partition plates 51 is arranged in the muzzle brake 38 to partition the space between the outer tubular portion 43 and the guiding outer tubular portion 44. A fourth gas-guiding hole 52 configured to pass the gas therethrough is formed in the partition plate 51.

The application of the fourth embodiment of the present invention is hereinafter described in order to develop an understanding of the present invention.

The motion of the gas and the reduction of repercussion at the time of firing are as follows.

Firstly, at the time of firing, a bullet is fired from the muzzle 40 and a part of the fired gas is diffused outside from the muzzle 40. The pressure created by the gas diffused outside serves as the repercussion which pushes the muzzle brake 39 and the gun barrel 38 posterior to a shooter.

Moreover, the gas having not been diffused outside passes through the first gas-guiding hole 53, and flows into the space between the inner tubular portion 42 and the outer tubular portion 44. Furthermore, a part of the gas having passed the first gas-guiding hole 53 is taken or received by the blocking portion 46, and exerts a pressure in the firing direction. The pressure serves as a force to push out the muzzle brake 39 and the gun barrel 38 in the firing direction.

Moreover, the gas having passed the first gas-guiding hole 53 flows to the second gas-guiding hole 47, passes through the second gas-guiding hole 47, flows into the space between the outer tubular portion 43 and the guiding outer tubular portion 44, and flows to the partition plate 51. The gas passes through the fourth gas-guiding hole 52 of the partition plate 51, and is guided to the space formed by the plurality of partition plates 51.

The gas having passed through the fourth gas-guiding hole 52 of the partition pate 51 is diffused outside from the third gas-guiding hole 49 that is formed in the blocking portion 48. Furthermore, the gas held inside the muzzle brake 39 is cooled and the pressure falls gradually. The gas is diffused outside slowly from the muzzle 40.

As described previously, in accordance with the third embodiment of the present invention, the pressure of the gas guided to the inside of the muzzle brake 39 is used to offset the repercussion caused by the pressure of the gas diffused outside, thereby reducing the repercussion exerted on the gun barrel 38.

By virtue of the gun barrel hole 41 and the first gas-guiding hole 53 corresponding to the gun barrel hole 41, the gas produced at the time of firing can be directly incorporated or introduced into the muzzle brake 39. Due to this, the effect of reducing the repercussion of the gas can be improved.

By virtue of the guiding outer tubular portion 44, the amount of the gas held inside can be increased, thereby being adapted to a large-caliber gun. In addition, by virtue of the partition plate 51, the cooling effect of the gas can be improved, and the repercussion can be reduced.

As mentioned above, the muzzle brake in accordance with the embodiments of the invention can efficiently reduce the influence of the gas at the time of firing. Moreover, the firearm to which any of the embodiments of the invention is applied can efficiently reduce the influence of the gas at the time of firing.

REFERENCE SIGNS LIST

-   1 muzzle brake -   2 inner tubular portion -   3 outer tubular portion -   4 lid portion -   5 gun barrel -   6 muzzle -   7 first gas-guiding hole -   8 piston -   9 spring -   10 stopper -   11 blocking portion -   12 large-caliber muzzle brake -   13 inner tubular portion -   14 outer tubular portion -   15 guiding outer tubular portion -   16 lid portion -   17 gun barrel -   18 second gas-guiding hole -   19 blocking portion -   20 third gas-guiding hole -   21 fixed configuration -   22 partition plate -   23 fourth gas-guiding hole -   24 muzzle -   25 simplified muzzle brake -   26 inner tubular portion -   27 outer tubular portion -   28 gun barrel -   29 first gas-guiding hole -   30 muzzle -   31 second gas-guiding hole -   32 protruding portion -   33 inclined surface -   34 blocking portion -   35 curved surface -   36 blocking portion -   37 gun -   38 gun barrel -   39 muzzle brake -   40 muzzle -   41 gun barrel hole -   42 inner tubular portion -   43 outer tubular portion -   44 guiding outer tubular portion -   45 screw fixing member -   46 blocking portion -   47 second gas-guiding hole -   48 blocking portion -   49 third gas-guiding hole -   50 blocking portion -   51 partition plate -   52 fourth gas-guiding hole -   53 first gas-guiding hole 

1. A muzzle brake, comprising: a substantially tubular inner wall portion having a first hole formed therein and in which a muzzle of a gun barrel that is inserted into the inner wall portion is located adjacent to the first hole and is capable of being fixed thereto; an outer wall portion substantially surrounding the inner wall portion; a first blocking portion arranged closer to a location into which the gun barrel is inserted than a location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a second blocking portion arranged more opposite to the first blocking portion than the location where the first hole is formed, and configured to block the clearance between the inner wall portion and the outer wall portion; a substantially tubular piston which is movable in a state where an area between the first hole and the first blocking portion comes in contact with the inner wall portion and the outer wall portion; and a piston-receiving member with an elasticity arranged between the piston and the first blocking portion and being movable in the area between the first hole and the first blocking portion.
 2. The muzzle brake according to claim 1, wherein the piston is rotatable, and a center of gravity is biased in the piston.
 3. The muzzle brake according to claim 1, further comprising a protruding portion located between the first hole and the piston, and protruding from the inner wall portion toward the outer wall portion.
 4. The muzzle brake according to claim 1, wherein the first blocking portion has a first openable and closable opening portion.
 5. The muzzle brake according to claim 1, wherein the outer wall portion has a second hole formed on a peripheral surface thereof and in an at least part of the area where the piston is movable, and comprises: a guiding outer wall portion substantially surrounding the outer wall portion; a third blocking portion located more closer to the location into which the gun barrel is inserted than a location where the second hole is formed, and configured to block a clearance between the outer wall portion and the guiding outer wall portion; a fourth blocking portion located more opposite to the third blocking portion than the location where the second hole is formed, and configured to block the clearance between the outer wall portion and the guiding outer wall portion; a second openable and closable opening formed in the third blocking portion; a third hole formed in the fourth blocking portion; and a partition portion having a fourth hole formed in at least a part thereof, and configured to block the clearance between the outer wall portion and the guiding outer wall portion.
 6. The muzzle brake according to claim 5, wherein the muzzle brake comprises a plurality of the partition portions, and wherein the neighboring partition portions are different from each other in an arrangement of the fourth hole in a plane which is substantially perpendicular to a lengthwise direction of the guiding outer wall portion.
 7. A muzzle brake, comprising: a substantially tubular inner wall portion having a first hole and a second hole spaced apart from the first hole, and in which a muzzle of a gun barrel that is inserted into the inner wall portion is located adjacent to the second hole and is capable of being fixed thereto; an outer wall portion substantially surrounding the inner wall portion; a first blocking portion arranged more opposite to a location into which the gun barrel is inserted than a location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a second blocking portion arranged closer to the location into which the gun barrel is inserted than a location where the second hole is formed, and configured to block the clearance between the inner wall portion and the outer wall portion; and a protruding portion located at the first hole adjacent the second hole on a peripheral surface of the inner wall portion and protruding from the inner wall portion toward the outer wall portion.
 8. A firearm, comprising: a gun barrel having a gun barrel hole formed in an area thereof adjacent to a muzzle, and a muzzle brake, which comprises: a substantially tubular inner wall portion having a first hole formed in an area thereof corresponding to the gun barrel hole, wherein the gun barrel is capable of being fixed to an inside of the inner wall portion; an outer wall portion substantially surrounding the inner wall portion and having a second hole formed closer to a location into which the gun barrel is inserted than a location where the first hole is formed; a first blocking portion arranged closer to the location into which the gun barrel is inserted than the location where the first hole is formed, and configured to block a clearance between the inner wall portion and the outer wall portion; a second blocking portion arranged more opposite to the first blocking portion than the location where the first hole is formed, and configured to block the clearance between the inner wall portion and the outer wall portion; a guiding outer wall portion substantially surrounding the outer wall portion; a third blocking portion located more closer to the location into which the gun barrel is inserted than a location where the second hole is formed, and configured to block a clearance between the outer wall portion and the guiding outer wall portion; a fourth blocking portion located more opposite to the third blocking portion than the location where the second hole is formed, and configured to block the clearance between the outer wall portion and the guiding outer wall portion; a third hole formed in the fourth blocking portion; and a partition portion having a fourth hole formed in at least a part thereof, and configured to block the clearance between the outer wall portion and the guiding outer wall portion.
 9. The muzzle brake according to claim 2, further comprising a protruding portion located between the first hole and the piston, and protruding from the inner wall portion toward the outer wall portion.
 10. The muzzle brake according to claim 2, wherein the first blocking portion has a first openable and closable opening portion. 